Comparación de secuencias volumétricas con técnicas convencionales en resonancia magnética de columna lumbar / Comparison of volumetric and conventional sequences for the evaluation in magnetic resonance of the lumbar spine

Objetivo: Comparar el protocolo que incluye la secuencia tridimensional SPACE-3D con el protocolo convencional en el estudio imagenológico por resonancia magnética (RM) del paciente con dolor lumbar. Metodología: Se realizó un estudio prospectivo de pruebas diagnósticas, en el que se tomaron imágenes por RM de la columna lumbar de 40 pacientes utilizando un protocolo convencional y otro protocolo que incluyera una secuencia volumétrica (SPACE-3D) en conjunto con secuencia axial con información T1 y sagital STIR, en un resonador de 1,5T. Las imágenes fueron interpretadas por dos radiólogos de manera independiente, empleando tanto el protocolo convencional como el protocolo que incluía la secuencia volumétrica, con un mes de diferencia. Se compararon ambos protocolos calculando la sensibilidad y la especificidad con el intervalo de confianza (IC 95 %), se consideró significación estadística un valor de p≤ 0,05 utilizando la prueba de Chi-cuadrado. Se evaluaron para ambas técnicas variables como presencia o no de artefactos, protrusión/extrusión discal, estrechez del canal neural central, receso lateral o foramen de emergencia radicular, radiculopatía. Se calculó la concordancia inter e intraobservador utilizando el índice Kappa con un IC 95 %. Resultados: Se encontró que el protocolo que incluye la secuencia SPACE-3D presenta rendimiento diagnóstico similar (no inferior) frente al protocolo con las secuencias convencionales para las variables evaluadas; igualmente, se detectaron los hallazgos anormales, lo cual permitió un estudio completo y un diagnóstico en menor tiempo. Conclusiones: El rendimiento diagnóstico del protocolo que incluye la secuencia volumétrica SPACE-3D es similar (no inferior) al protocolo con las secuencias convencionales utilizadas en RM de columna lumbar y acorta el tiempo total del estudio

Objective: To compare the protocol that includes the three-dimensional SPACE-3D sequence with the conventional protocol in the magnetic resonance imaging (MRI) study of patients with low back pain. Methods: A prospective study of diagnostic tests was carried out, in which MR images of the lumbar spine were taken from 40 patients using a conventional protocol and another protocol that included a volumetric sequence (SPACE-3D) in conjunction with axial T1 and sagittal STIR sequences, in a 1.5T resonator. The images were interpreted by two radiologists independently, both the conventional protocol and the protocol that included the volumetric sequence, one month apart. Both protocols were compared, calculating the sensitivity and specificity with the confidence interval (CI 95%), a value of p ≤0.05 using the Chi-square test was considered statistically significant. Variables such as the presence or absence of artifacts, disc protrusion/extrusion, narrowing of the central neural canal, lateral recess or root emergence foramen, and presence of radiculopathy, among others, were evaluated for both techniques. Inter- and intra-observer agreement was calculated using the Kappa index with a 95% CI. Results: it was found that the protocol that included the SPACE-3D sequence presents similar diagnostic performance (not inferior) when compared to the protocol with the conventional sequences for the variables evaluated, similarly, abnormal findings were detected, which allowed a complete study and diagnosis in less time. Conclusions: The diagnostic performance of the protocol that includes the SPACE-3D volumetric sequence is similar (not inferior) to the protocol with conventional sequences used in MRI of the lumbar spine and shortens the total study time.

Orbital soft tissue composite lymphoma presenting as recurrence of a nodal lymphoma with mantle and follicular cell components: a case report, literature review and guideline for the treatment of patients / Linfoma compuesto de tejidos blandos orbitario presentándose como recurrencia de un linfoma ganglionar con componentes del manto y folicular: descripción de un caso, revisión de la literatura y guía para el tratamiento de los pacientes

Composite lymphoma with mantle and follicular cell components is a challenging diagnosis. Flow cytometry, immunohistochemistry and molecular genetics are required to distinguish the two components, as often the more aggressive one is predominant and masks the other. A 58-year-old man with history of nodal composite lymphoma presented with right exophthalmos and diplopia. A head CT scan showed an orbital tumor. A biopsy of the tumor revealed a mantle cell lymphoma predominating over a follicular lymphoma. Immunoglobulin heavy chain and light chain rearrangements analysis by PCR proved that both components of the orbital tumor were recurrences of the same nodal composite lymphoma diagnosed two years earlier. The nodal lymphoma was composed of a follicular lymphoma and an in situ mantle cell neoplasia. Consensus view is that dominant lymphoma should be treated when needed but taking into account if the mantle cell lymphoma is an in situ neoplasia and if it expresses CD5 and SOX11

El diagnóstico de linfoma compuesto con componentes del manto y folicular es desafiante y requiere de técnicas como citometría de flujo, inmunohistoquímica y genética molecular, porque a menudo el componente linfoide más agresivo predomina sobre el otro, enmascarándolo. Un varón de 58 años con historia de linfoma compuesto ganglionar presentó exoftalmos derecho y diplopia. La TAC de cabeza mostró un tumor orbitario. Una biopsia del tumor reveló un linfoma del manto predominando sobre un linfoma folicular. El reordenamiento genético mediante PCR de la cadena pesada y cadenas ligeras de inmunoglobulina demostró que ambos componentes del tumor orbitario eran recurrentes del mismo linfoma compuesto ganglionar diagnosticado 2 años antes. El linfoma ganglionar estaba compuesto por linfoma folicular y neoplasia del manto in situ. El consenso es que el linfoma dominante debe ser tratado cuando sea necesario considerando si el linfoma del manto es in situ y si expresa CD5 y SOX11

Orbital soft tissue composite lymphoma presenting as recurrence of a nodal lymphoma with mantle and follicular cell components: A case report, literature review and guideline for the treatment of patients.

Composite lymphoma with mantle and follicular cell components is a challenging diagnosis. Flow cytometry, immunohistochemistry and molecular genetics are required to distinguish the two components, as often the more aggressive one is predominant and masks the other. A 58-year-old man with history of nodal composite lymphoma presented with right exophthalmos and diplopia. A head CT scan showed an orbital tumor. A biopsy of the tumor revealed a mantle cell lymphoma predominating over a follicular lymphoma. Immunoglobulin heavy chain and light chain rearrangements analysis by PCR proved that both components of the orbital tumor were recurrences of the same nodal composite lymphoma diagnosed two years earlier. The nodal lymphoma was composed of a follicular lymphoma and an in situ mantle cell neoplasia. Consensus view is that dominant lymphoma should be treated when needed but taking into account if the mantle cell lymphoma is an in situ neoplasia and if it expresses CD5 and SOX11.

Anisotropic Ordering in 1T' Molybdenum and Tungsten Ditelluride Layers Alloyed with Sulfur and Selenium.

Alloying is an effective way to engineer the band-gap structure of two-dimensional transition-metal dichalcogenide materials. Molybdenum and tungsten ditelluride alloyed with sulfur or selenium layers (MX2xTe2(1-x), M = Mo, W and X = S, Se) have a large band-gap tunability from metallic to semiconducting due to the 2H-to-1T' phase transition as controlled by the alloy concentrations, whereas the alloy atom distribution in these two phases remains elusive. Here, combining atomic resolution Z-contrast scanning transmission electron microscopy imaging and density functional theory (DFT), we discovered that anisotropic ordering occurs in the 1T' phase, in sharp contrast to the isotropic alloy behavior in the 2H phase under similar alloy concentration. The anisotropic ordering is presumably due to the anisotropic bonding in the 1T' phase, as further elaborated by DFT calculations. Our results reveal the atomic anisotropic alloyed behavior in 1T' phase layered alloys regardless of their alloy concentration, shining light on fine-tuning their physical properties via engineering the alloyed atomic structure.

Role of Hydrogen Bonding on Transport of Coadsorbed Gases in Metal-Organic Frameworks Materials.

Coadsorption of multicomponents in metal-organic framework (MOF) materials can lead to a number of cooperative effects, such as modification of adsorption sites or during transport. In this work, we explore the incorporation of NH3 and H2O into MOFs preloaded with small molecules such as CO, CO2, and SO2. We find that NH3 (or H2O) first displaces a certain amount of preadsorbed molecules in the outer portion of MOF crystallites, and then substantially hinders diffusion. Combining in situ spectroscopy with first-principles calculations, we show that hydrogen bonding between NH3 (or H2O) is responsible for an increase of a factor of 7 and 8 in diffusion barrier of CO and CO2 through the MOF channels. Understanding such cooperative effects is important for designing new strategies to enhance adsorption in nanoporous materials.

Novel Pd_{2}Se_{3} Two-Dimensional Phase Driven by Interlayer Fusion in Layered PdSe_{2}.

Two-dimensional (2D) materials are easily fabricated when their bulk form has a layered structure. The monolayer form in layered transition-metal dichalcogenides is typically the same as a single layer of the bulk material. However, PdSe_{2} presents a puzzle. Its monolayer form has been theoretically shown to be stable, but there have been no reports that monolayer PdSe_{2} has been fabricated. Here, combining atomic-scale imaging in a scanning transmission electron microscope and density functional theory, we demonstrate that the preferred monolayer form of this material amounts to a melding of two bulk monolayers accompanied by the emission of Se atoms so that the resulting stoichiometry is Pd_{2}Se_{3}. We further verify the interlayer melding mechanism by creating Se vacancies in situ in the layered PdSe_{2} matrix using electron irradiation. The discovery that strong interlayer interactions can be induced by defects and lead to the formation of new 2D materials opens a new venue for the exploration of defect engineering and novel 2D structures.

Neumatosis intestinal: ¿una urgencia abdominal? / Cystic pneumatosis intestinalis: an emergency?

Resumen El auge de las imágenes diagnósticas, en especial de la tomografía computarizada multidetector ha permitido que entidades poco conocidas sean detectadas con relativa frecuencia. Inicialmente, se creía que todos los pacientes con neumatosis intestinal padecían enfermedades abdominales graves o presentaban complicaciones que requerían un manejo quirúrgico inmediato, pero al conocer mejor esta entidad, en parte gracias al aumento en el número de tomografías realizadas en la práctica diaria, se ha demostrado que la neumatosis intestinal también puede presentarse en pacientes asintomáticos o asociada a entidades benignas. Es importante conocer los signos y síntomas que ayudan a diferenciar las formas benignas de neumatosis de aquellas que ponen en peligro la vida del paciente y requieren manejo quirúrgico. Presentamos dos casos de neumatosis intestinal y una revisión de la literatura que ayudarán a aclarar la presentación por imágenes y etiología de esta entidad poco conocida.

Abstract Penumatosis intestinalis is a clinical condition that has been increasingly detected in recent years with the escalating use of computed tomography for abdominal imaging. Previously, it was thought that all the patients cursing with penumatosis intestinalis had life threatening conditions that required immediate surgical treatment. With the increased detection of this radiologic entity, benign causes have been described for example the cystic pneumatosis intestinalis, which in the mayority of times is an isolated finding and does not require surgery. It is important to recognize the signs and symptoms that help differentiate the benign forms, from those that are life-threatening conditions and require surgery. We report two cases of pneumatosis cystoides and a review of the literature that will illustrate the imaging findings and etiology of this rare entity.

Design of Optimally Stable Molecular Coatings for Fe-Based Nanoparticles in Aqueous Environments.

Magnetic nanoparticles are widely used in biomedical and oil-well applications in aqueous, often harsh environments. The pursuit for high-saturation magnetization together with high stability of the molecular coating that prevents agglomeration and oxidation remains an active research area. Here, we report a detailed analysis of the criteria for the stability of molecular coatings in aqueous environments along with extensive first-principles calculations for magnetite, which has been widely used, and cementite, a promising emerging candidate. A key result is that the simple binding energies of molecules cannot be used as a definitive indicator of relative stability in a liquid environment. Instead, we find that H+ ions and water molecules facilitate the desorption of molecules from the surface. We further find that, because of differences in the geometry of crystal structures, molecules generally form stronger bonds on cementite surfaces than they do on magnetite surfaces. The net result is that molecular coatings of cementite nanoparticles are more stable. This feature, together with the better magnetic properties, makes cementite nanoparticles a promising candidate for biomedical and oil-well applications.

Aproximación diagnóstica de las fístulas perianales por resonancia magnética / Diagnostic Approach to Perianal Fistulas with Magnetic Resonance

La enfermedad fistulosa perianal es una entidad inflamatoria crónica que afecta el canal anal y los espacios perianales. Las fístulas anales presentan gran morbilidad y recurrencia. Para definir el tipo de tratamiento quirúrgico o médico, evitar recurrencias y complicaciones como la incontinencia fecal, es importante una adecuada caracterización y clasificación de las fístulas mediante la resonancia magnética (RM). Actualmente la RM es el estudio imaginológico con mayor sensibilidad diagnóstica debido a su alta resolución anatómica para definir las estructuras del canal anal y demostrar el trayecto fistuloso con sus complicaciones (abscesos y trayectos secundarios).

Fistulous perianal disease is an inflammatory entity that affects the anal canal and perianal spaces. Anal fistulas represent important morbidity and recurrence for patients. For the planning of surgical treatment, preventing recurrences and complications like fecal incontinence, a proper characterization and classification of fistulas with magnetic resonance must be done. Currently, magnetic resonance is the imaging modality with greatest diagnostic sensitivity due to its high anatomical resolution in defining structures like the anal canal and fistulous tracts with its complications (abscesses, secondary paths).

Angiosarcoma de la mama: Presentación de dos casos / Angiosarcoma of the Breast: Report of Two Cases

Los angiosarcomas de la mama son tumores raros que conforman menos del 1 % de las neoplasias mamarias. Estos tumores pueden desarrollarse de forma primaria o secundaria y se han descrito 219 casos en la literatura mundial desde el primer caso informado por Schmidt en 1887. A continuación se presentan dos casos de angiosarcoma primario de la mama y sus principales características en los diferentes métodos diagnósticos.

Angiosarcomas are rare tumors that make up less than 1% of breast cancers. These tumors may develop in a primary or secondary form, and 219 cases have been reported in the literature since the first case described by Schmidt in 1887. Here we present two cases of primary angiosarcoma of the breast and its main features in different imaging modalities

Anomalías congénitas y variantes anatómicas del seno coronario / Congenital Anomalies and Anatomical Variants of Coronary Sinus

El seno coronario (SC) es la estructura vascular que permite el acceso a las venas coronarias en procedimientos intervencionistas como el mapeo y la ablación de arritmias, la implantación de electrodos izquierdos en terapia de resincronización, anuloplastia mitral, tratamiento con células madre y cardioplejía retrógrada. El éxito de estos procedimientos depende del conocimiento de la anatomía del SC, del reconocimiento de sus variantes y anomalías. La tomografía multicorte permite obtener imágenes de la anatomía del SC sin necesidad de procedimientos invasivos de diagnóstico. La resonancia magnética, por su condición no invasiva y sin radiación, también es útil en la evaluación del seno coronario porque permite la valoración morfológica y funcional de diversas anomalías congénitas del corazón.

The coronary sinus (CS) is an important vascular structure that allows access to the coronary veins in multiple interventional procedures such as mapping and ablation of arrhythmias, implantation of left ventricular electrodes in resynchronization therapy, mitral annuloplasty, stem cells therapy, and retrograde cardioplegia. The success of these procedures is facilitated by the knowledge of the CS anatomy, in particular the recognition of its variants and anomalies. The widespread availability of multislice CT (MSCT) allows non-invasive image acquisition with excellent representation of the CS anatomy, avoiding thus the need for invasive diagnostic procedures. MRI is also useful for the non-invasive evaluation of the coronary sinus, without radiation, allowing the morphological and functional assessment of various congenital heart abnormalities.

Trapping gases in metal-organic frameworks with a selective surface molecular barrier layer.

The main challenge for gas storage and separation in nanoporous materials is that many molecules of interest adsorb too weakly to be effectively retained. Instead of synthetically modifying the internal surface structure of the entire bulk-as is typically done to enhance adsorption-here we show that post exposure of a prototypical porous metal-organic framework to ethylenediamine can effectively retain a variety of weakly adsorbing molecules (for example, CO, CO2, SO2, C2H4, NO) inside the materials by forming a monolayer-thick cap at the external surface of microcrystals. Furthermore, this capping mechanism, based on hydrogen bonding as explained by ab initio modelling, opens the door for potential selectivity. For example, water molecules are shown to disrupt the hydrogen-bonded amine network and diffuse through the cap without hindrance and fully displace/release the retained small molecules out of the metal-organic framework at room temperature. These findings may provide alternative strategies for gas storage, delivery and separation.

Synthesis of the Privileged 8-Arylmenthol Class by Radical Arylation of Isopulegol.

Hydrogen atom transfer (HAT) circumvents a disfavored Friedel-Crafts reaction in the derivatization of the inexpensive monoterpene isopulegol. A variety of readily prepared aryl and heteroaryl sulfonates undergo a formal hydroarylation to form 8-arylmenthols, privileged scaffolds for asymmetric synthesis, as typified by 8-phenylmenthol. High stereoselectivity is observed in related systems. This use of HAT significantly extends the chiral pool from the inexpensive monoterpene isopulegol.

Linfoma primario del mediastino (tímico): Presentación de caso / Primary Mediastinal Lymphoma (Thymic): A Case Report

Los linfomas mediastinales anteriores pueden hacer parte del linfoma sistémico y comprenden aproximadamente el 50 % de los tumores mediastinales. El linfoma no Hodgkin primario del mediastino es un subtipo de menor prevalencia, representando un 10 % de los casos; este tiene dos subtipos histológicos que son el linfoma T linfoblástico y el linfoma B difuso de célula grande. Este último es agresivo y tiende a infiltrar la pleura, las estructuras óseas y el pulmón; se origina de las células B de la médula del timo. En este artículo se describe un caso de linfoma no Hodgkin primario del mediastino del subtipo B difuso de células grandes, sus hallazgos por imágenes, patología y una breve revisión de la literatura.

Anterior mediastinal lymphomas may be part of systemic lymphoma and they comprise approximately 50 % of mediastinal neoplasms. Primary non-Hodgkin's lymphoma of the mediastinum is a subtype with lower prevalence, representing 10 % of all cases; it has two histologic subtypes that include T-cell lymphoblastic lymphoma and diffuse large B-cell lymphoma. The latter is an aggressive neoplasm that tends to infiltrate the pleura, bone structures and the lung; it originates from thymic medullary B cells. This article presents a case of primary non-Hodgkin's lymphoma of the mediastinum with diffuse large B-cell subtype, its radiologic findings, pathology and a brief review of the literature.

Rapid synthesis and antimicrobial activity of novel 4-oxazolidinone heterocycles.

The synoxazolidinone family of marine natural products bear an unusual 4-oxazolidinone heterocyclic core and promising antimicrobial activity against several strains of pathogenic bacteria. As part of our research program directed at the synthesis and chemical biology of this family of natural products we have developed a one-step method for the generation of variously substituted 4-oxazolidinone scaffolds from readily available materials. These studies revealed the importance of an electron deficient aromatic ring for antimicrobial activity and serve as the basis for future SAR studies around the 4-oxazolidinone core.

Structural band-gap tuning in g-C3N4.

g-C3N4 is a promising material for hydrogen production from water via photo-catalysis, if we can tune its band gap to desirable levels. Using a combined experimental and ab initio approach, we uncover an almost perfectly linear relationship between the band gap and structural aspects of g-C3N4, which we show to originate in a changing overlap of wave functions associated with the lattice constants. This changing overlap, in turn, causes the unoccupied pz states to experience a significantly larger energy shift than any other occupied state (s, px, or py), resulting in this peculiar relationship. Our results explain and demonstrate the possibility to tune the band gap by structural means, and thus the frequency at which g-C3N4 absorbs light.

Hamartoma mesenquimal multifocal de la pared torácica: Presentación de caso / Multifocal Mesenchymal Hamartoma of the Chest Wall: A Case Report

Los hamartomas mesenquimales de la pared torácica son lesiones raras que generalmente se presentan en la infancia temprana y que se manifiestan como una masa que deforma la pared torácica y puede acompañarse de disnea. Hasta el momento, en la literatura mundial se ha informado de 100 casos, aproximadamente. Los diferentes métodos de imagen, como la radiografía de tórax, la tomografía computarizada (TC) o la resonancia magnética son útiles para realizar el diagnóstico; sin embargo, la TC es más útil en el diagnóstico, porque logra demostrar el origen óseo y las calcificaciones intralesionales. Es importante conocer las características imaginológicas de este tipo de lesiones, ya que pueden ser fácilmente confundidas con un tumor maligno.

Mesenchymal hamartomas of the chest wall are extremely rare lesions that usually affect children and newborns and whose most common manifestation is a large mass that deforms the chest wall and can cause dyspnea. Up to this date, approximately 100 cases have been reported worldwide in the literature. Different imaging methods such as chest X-ray, computed tomography (CT) or magnetic resonance imaging (MRI) are useful for diagnosis; nevertheless, CT is the best in diagnostic aid because it manages to demonstrate bony origin and intralesional calcifications. It is important to identify the imaginological features of such lesions because they can easily be mistaken for a malignant tumor.

Study of van der Waals bonding and interactions in metal organic framework materials.

Metal organic framework (MOF) materials have attracted a lot of attention due to their numerous applications in fields such as hydrogen storage, carbon capture and gas sequestration. In all these applications, van der Waals forces dominate the interaction between the small guest molecules and the walls of the MOFs. In this review article, we describe how a combined theoretical and experimental approach can successfully be used to study those weak interactions and elucidate the adsorption mechanisms important for various applications. On the theory side, we show that, while standard density functional theory is not capable of correctly describing van der Waals interactions, functionals especially designed to include van der Waals forces exist, yielding results in remarkable agreement with experiment. From the experimental point of view, we show examples in which IR adsorption and Raman spectroscopy are essential to study molecule/MOF interactions. Importantly, we emphasize throughout this review that a combination of theory and experiment is crucial to effectively gain further understanding. In particular, we review such combined studies for the adsorption mechanism of small molecules in MOFs, the chemical stability of MOFs under humid conditions, water cluster formation inside MOFs, and the diffusion of small molecules into MOFs. The understanding of these phenomena is critical for the rational design of new MOFs with desired properties.